headcount

More generally, a consideration of a company's appropriate staffing level based on some larger context. (Generally used adjectivally.)

By extension, one slot in a workgroup, filled or to be filled by one person.

Usage notes

The two-word spelling head count refers neutrally to simple counts. The one-word spelling headcount tends to have a business jargon feel to it, especially when used adjectivally in phrases such as "headcount reduction", or in the extrapolated case where it refers to one person or one job opening.